All organisms need energy to live and grow. Energy is gained from food!! Roles that organisms serve in ecosystems are based on how they get their energy.
Organisms that make, or produce their food. Plants are called producers because they are able to use light energy from the Sun to produce food (sugar) from carbon dioxide in the air and water.
Organisms that must eat, or consume plants or animals for food. They cannot make their own food. Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers. There are three main groups of consumers. Animals that eat only plants are called herbivores. Animals that eat only animals are called carnivores. Animals that eat both animals and plants are called omnivores.
Tiny living things that break down dead organisms and return nutrients to the soil. Consumers (including microorganisms, termites, worms, and fungi) that get the energy they need by breaking down dead or decaying matter. These decomposers speed up the decaying process that releases nutrients back into the food chain for use by plants.
A food chain is a series of plants and animals in which each organism is a source of food (energy) for the next in the series. In a typical food chain, plants use the Sun’s energy to make their own food and then are eaten by one kind of animal which in turn is eaten by another kind of animal.
Most organisms are part of more than one food chain and eat more than one kind of food in order to meet their energy requirements. Interconnected food chains form a food web! A food web shows how a group of food chains are linked together.
Most food chains have NO more than six organisms. There cannot be too many links in a single food chain because the animals at the end of the chain would not get enough food (energy) to stay alive. The role of an organism can be identified by its placement on the food chain. Decomposers are not typically notes on a food chain; they will break down ANY dead organism on the food chain when it dies.
Organisms can also be identified based on how they interact with other organisms: Predators are animals that hunt and kill other animals for food. Prey are animals that are hunted and killed as food for other animals. A parasite is an organism that spends a significant portion of its life in or on a living host organism, usually causing harm to the host without immediately killing it. Hosts are organisms or cells that serve as a home or a source of food for a parasite.